If you have any questions you think should be answered in this document,
please let me know.
- --drepper@cygnus.com
+ --drepper@redhat.com
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1.19. `make' complains about a missing dlfcn/libdl.so when building
malloc/libmemprof.so. How can I fix this?
1.20. Which tools should I use for MIPS?
+1.21. Which compiler should I use for powerpc64?
2. Installation and configuration issues
2.33. The makefiles want to do a CVS commit.
2.34. When compiling C++ programs, I get a compilation error in streambuf.h.
2.35. When recompiling GCC, I get compilation errors in libio.
+2.36. Why shall glibc never get installed on GNU/Linux systems in
+/usr/local?
+2.37. When recompiling GCC, I get compilation errors in libstdc++.
3. Source and binary incompatibilities, and what to do about them
when I try to use it, it always returns -1 and sets errno to ENOSYS.
3.22. My program segfaults when I call fclose() on the FILE* returned
from setmntent(). Is this a glibc bug?
+3.23. I get "undefined reference to `atexit'"
4. Miscellaneous
4.8. The conversion table for character set XX does not match with
what I expect.
4.9. How can I find out which version of glibc I am using in the moment?
+4.10. Context switching with setcontext() does not work from within
+ signal handlers.
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m68k-*-linux-gnu Linux-2.x on Motorola 680x0
alpha*-*-linux-gnu Linux-2.x on DEC Alpha
powerpc-*-linux-gnu Linux and MkLinux on PowerPC systems
+ powerpc64-*-linux-gnu Linux-2.4+ on 64-bit PowerPC systems
sparc-*-linux-gnu Linux-2.x on SPARC
sparc64-*-linux-gnu Linux-2.x on UltraSPARC
arm-*-none ARM standalone systems
mips*-*-linux-gnu Linux-2.x on MIPS
ia64-*-linux-gnu Linux-2.x on ia64
s390-*-linux-gnu Linux-2.x on IBM S/390
+ s390x-*-linux-gnu Linux-2.x on IBM S/390 64-bit
+ cris-*-linux-gnu Linux-2.4+ on CRIS
Ports to other Linux platforms are in development, and may in fact work
already, but no one has sent us success reports for them. Currently no
You should always try to use the latest official release. Older versions
may not have all the features GNU libc requires. The current releases of
-gcc (2.95 or newer) should work with the GNU C library (for powerpc see
-question 1.5; for ARM see question 1.6; for MIPS see question 1.20).
+gcc (3.2 or newer) should work with the GNU C library (for MIPS see question 1.20).
Please note that gcc 2.95 and 2.95.x cannot compile glibc on Alpha due to
problems in the complex float support.
The static library can be compiled with less featureful tools, but lacks key
features such as NSS.
-For Linux or Hurd, you want binutils 2.8.1.0.23, 2.9.1, or 2.9.1.0.15 or
-higher. These are the only versions we've tested and found reliable. Other
-versions after 2.8.1.0.23 may work but we don't recommend them, especially
-not when C++ is involved. Earlier versions do not work at all.
+For Linux or Hurd, you want binutils 2.13 or higher. These are the only
+versions we've tested and found reliable. Other versions may work but we
+don't recommend them, especially not when C++ is involved.
Other operating systems may come with system tools that have all the
necessary features, but this is moot because glibc hasn't been ported to
1.5. Which compiler should I use for powerpc?
-{GK} You want to use at least gcc 2.95 (together with the right versions
-of all the other tools, of course). See also question question 2.8.
+{} Removed. Does not apply anymore.
1.6. Which tools should I use for ARM?
-{PB} You should use egcs 1.1 or a later version. For ELF systems some
-changes are needed to the compiler; a patch against egcs-1.1.x can be found
-at:
-
-<ftp://ftp.netwinder.org/users/p/philb/egcs-1.1.1pre2-diff-981126>
-
-Binutils 2.9.1.0.16 or later is also required.
+{} Removed. Does not apply anymore.
1.7. Do I need some more things to compile the GNU C Library?
`message catalog' files containing translated versions of system
messages. See ftp://ftp.gnu.org/pub/gnu or better any mirror
site. (We distribute compiled message catalogs, but they may not be
- updated in patches.) Please note that the required minimal version
- (0.10.35) of gettext is alpha software and available from
- ftp://alpha.gnu.org/gnu .
+ updated in patches.)
* Some files are built with special tools. E.g., files ending in .gperf
need a `gperf' program. The GNU version (now available in a separate
There are some failures which are not directly related to the GNU libc:
- Some compilers produce buggy code. No compiler gets single precision
- complex numbers correct on Alpha. Otherwise, the egcs 1.1 release should be
- ok; gcc 2.8.1 might cause some failures; gcc 2.7.2.x is so buggy that
- explicit checks have been used so that you can't build with it.
+ complex numbers correct on Alpha. Otherwise, gcc-3.2 should be ok.
- The kernel might have bugs. For example on Linux/Alpha 2.0.34 the
floating point handling has quite a number of bugs and therefore most of
the test cases in the math subdirectory will fail. Linux 2.2 has
1.20. Which tools should I use for MIPS?
-{AJ} You should use the current development version of gcc 2.97 from CVS.
-gcc 2.95.x does not work correctly on mips-linux.
+{AJ} You should use the current development version of gcc 3.2 or newer from
+CVS.
+
+You need also recent binutils, anything before and including 2.11 will not
+work correctly. Either try the Linux binutils 2.11.90.0.5 from HJ Lu or the
+current development version of binutils from CVS.
-You need also recent binutils, anything before and including 2.10 will not
-work correctly. Either try the Linux binutils 2.10.0.33 from HJ Lu or the
-current development version from CVS of binutils.
+Please note that `make check' might fail for a number of the math tests
+because of problems of the FPU emulation in the Linux kernel (the MIPS FPU
+doesn't handle all cases and needs help from the kernel).
For details check also my page <http://www.suse.de/~aj/glibc-mips.html>.
+
+1.21. Which compiler should I use for powerpc64?
+
+{SM} You want to use at least gcc 3.2 (together with the right versions
+of all the other tools, of course).
+
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
glibc 2.x?
{AJ} There's only correct support for glibc 2.0.x in gcc 2.7.2.3 or later.
-But you should get at least gcc 2.95.2.1 (or later versions) instead.
+But you should get at least gcc 2.95.3 (or later versions) anyway
2.10. The `gencat' utility cannot process the catalog sources which
-----------------------------------------------------------------------
# Change catalog source in Linux specific format to standard XPG format.
-# Ulrich Drepper <drepper@cygnus.com>, 1996.
+# Ulrich Drepper <drepper@redhat.com>, 1996.
#
/^\$ #/ {
h
`db-Makefile' in the subdirectory `nss' and you can call it with `make -f
db-Makefile'. Please note that not all services are capable of using a
database. Currently passwd, group, ethers, protocol, rpc, services shadow
-and netgroup are implemented. See also question question 2.31.
+and netgroup are implemented. See also question 2.31.
2.17. I have /usr/include/net and /usr/include/scsi as symlinks
If it has been in use, it should be switched off.
- Programs using IPv6 have to be recompiled due to incompatible changes in
sockaddr_in6 by the IPv6 working group.
-- The Berkeley db libraries have been removed (for details see ??nssdb).
+- The Berkeley db libraries have been removed (for details see question 2.31).
- The format of the locale files has changed, all locales should be
regenerated with localedef. All statically linked applications which use
i18n should be recompiled, otherwise they'll not be localized.
{BH} You are using g++ 2.95.2? After upgrading to glibc 2.2, you need to
apply a patch to the include files in /usr/include/g++, because the fpos_t
type has changed in glibc 2.2. The patch is at
-http://clisp.cons.org/~haible/gccinclude-glibc-2.2-compat.diff
+
+ http://www.haible.de/bruno/gccinclude-glibc-2.2-compat.diff
2.35. When recompiling GCC, I get compilation errors in libio.
-{BH} You are trying to recompile gcc 2.95.2? Use gcc 2.95.2.1 instead.
+{BH} You are trying to recompile gcc 2.95.2? Use gcc 2.95.3 instead.
This version is needed because the fpos_t type and a few libio internals
-have changed in glibc 2.2, and gcc 2.95.2.1 contains a corresponding patch.
+have changed in glibc 2.2, and gcc 2.95.3 contains a corresponding patch.
+
+
+2.36. Why shall glibc never get installed on GNU/Linux systems in
+/usr/local?
+
+{AJ} The GNU C compiler treats /usr/local/include and /usr/local/lib in a
+special way, these directories will be searched before the system
+directories. Since on GNU/Linux the system directories /usr/include and
+/usr/lib contain a --- possibly different --- version of glibc and mixing
+certain files from different glibc installations is not supported and will
+break, you risk breaking your complete system. If you want to test a glibc
+installation, use another directory as argument to --prefix. If you like to
+install this glibc version as default version, overriding the existing one,
+use --prefix=/usr and everything will go in the right places.
+
+
+2.37. When recompiling GCC, I get compilation errors in libstdc++.
+
+{BH} You are trying to recompile gcc 3.2? You need to patch gcc 3.2,
+because some last minute changes were made in glibc 2.3 which were not
+known when gcc 3.2 was released. The patch is at
+
+ http://www.haible.de/bruno/gcc-3.2-glibc-2.3-compat.diff
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
won't always work. Unfortunately, for compatibility reasons, we can't
change the return type of setmntent() to something other than FILE *.
+
+3.23. I get "undefined reference to `atexit'"
+
+{UD} This means that your installation is somehow broken. The situation is
+the same as for 'stat', 'fstat', etc (see question 2.7). Investigate why the
+linker does not pick up libc_nonshared.a.
+
+If a similar message is issued at runtime this means that the application or
+DSO is not linked against libc. This can cause problems since 'atexit' is
+not exported anymore.
+
\f
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
This interface can also obviously be used to perform tests at runtime if
this should be necessary.
+
+4.10. Context switching with setcontext() does not work from within
+ signal handlers.
+
+{DMT} The Linux implementations (IA-64, S390 so far) of setcontext()
+supports synchronous context switches only. There are several reasons for
+this:
+
+- UNIX provides no other (portable) way of effecting a synchronous
+ context switch (also known as co-routine switch). Some versions
+ support this via setjmp()/longjmp() but this does not work
+ universally.
+
+- As defined by the UNIX '98 standard, the only way setcontext()
+ could trigger an asychronous context switch is if this function
+ were invoked on the ucontext_t pointer passed as the third argument
+ to a signal handler. But according to draft 5, XPG6, XBD 2.4.3,
+ setcontext() is not among the set of routines that may be called
+ from a signal handler.
+
+- If setcontext() were to be used for asynchronous context switches,
+ all kinds of synchronization and re-entrancy issues could arise and
+ these problems have already been solved by real multi-threading
+ libraries (e.g., POSIX threads or Linux threads).
+
+- Synchronous context switching can be implemented entirely in
+ user-level and less state needs to be saved/restored than for an
+ asynchronous context switch. It is therefore useful to distinguish
+ between the two types of context switches. Indeed, some
+ application vendors are known to use setcontext() to implement
+ co-routines on top of normal (heavier-weight) pre-emptable threads.
+
+It should be noted that if someone was dead-bent on using setcontext()
+on the third arg of a signal handler, then IA-64 Linux could support
+this via a special version of sigaction() which arranges that all
+signal handlers start executing in a shim function which takes care of
+saving the preserved registers before calling the real signal handler
+and restoring them afterwards. In other words, we could provide a
+compatibility layer which would support setcontext() for asynchronous
+context switches. However, given the arguments above, I don't think
+that makes sense. setcontext() provides a decent co-routine interface
+and we should just discourage any asynchronous use (which just calls
+for trouble at any rate).
+
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Answers were given by:
-{UD} Ulrich Drepper, <drepper@cygnus.com>
-{DMT} David Mosberger-Tang, <davidm@AZStarNet.com>
+{UD} Ulrich Drepper, <drepper@redhat.com>
+{DMT} David Mosberger-Tang, <davidm@hpl.hp.com>
{RM} Roland McGrath, <roland@gnu.org>
{AJ} Andreas Jaeger, <aj@suse.de>
{EY} Eric Youngdale, <eric@andante.jic.com>
{MK} Mark Kettenis, <kettenis@phys.uva.nl>
{ZW} Zack Weinberg, <zack@rabi.phys.columbia.edu>
{TK} Thorsten Kukuk, <kukuk@suse.de>
-{GK} Geoffrey Keating, <geoffk@ozemail.com.au>
+{GK} Geoffrey Keating, <geoffk@redhat.com>
{HJ} H.J. Lu, <hjl@gnu.org>
{CG} Cristian Gafton, <gafton@redhat.com>
-{AO} Alexandre Oliva, <oliva@lsd.ic.unicamp.br>
+{AO} Alexandre Oliva, <aoliva@redhat.com>
{BH} Bruno Haible, <haible@clisp.cons.org>
+{SM} Steven Munroe, <sjmunroe@us.ibm.com>
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